This is a big scam, as far as I can see.. I lived in an unencorperated community in So Ca and these guys would come around every year wanting to paint my curb numbers.. Claimed it was required but the local (county) fire dept... I only let them paint mine once and noticed that they were using ordinary lacquar spay paint.. Like you would use on a craft project.
The next time the came around I refused unless they could show me the law and spec. on their paint, that it was for outside use. They could provide neither.
They would still come around each year, but I had already painted my own with a brush, stencil and exterior paint.
Wouldn't be so bad if they were truly working to raise funds for the fire dept. but they are just scammers, like the drive way sealers.
Steve